1. Field
This invention relates to hammermill crushers, which are used in the mineral industries for reducing the size of aggregate to a fine size, i.e., a mesh size of about 8 to about 200. Because of the fineness of the mill product, "dusting" or loss of fine material has been a long-standing problem. The "dusting" of "fines" lost from the mill may present a maintenance and/or cleaning problem in production equipment. Furthermore, for a mill in a sampling line the loss of any material may introduce an error into the sample analyses. Part of the dusting problem results because conventional hammermills act as an air-pump, drawing air into the system by the rapid rotation of the hammers.
Introduction of large quantities of air into a particulate sampling system further aggrevates the dusting problem and tends to dry the particulate material, which causes an erroneous indication of moisture content. Although these problems have existed, hammermills have an important function in particulate sampling systems because of their compactness, efficiency in reducing particle size, reliability in producing particles of a constant size distribtuion and uniformity of size, and ability to effect a substantial particle size reduction to a fine particle size.